Edwards, try the following code, based on an old example. It fails on Intel machine but it's fine on my PPC "lamp" iMac. It seems that the undocumented IOFBBeamPosition function is not working on Intel. Michele. include "Rntm Lite.incl" include library "IOKit/graphics/IOGraphicsLib.h" #if ndef _DEFINEDINCARBON #define io_connect_t as ptr #define IOReturn as kern_return_t toolbox fn IOPSAllocateBlitEngine( io_connect_t framebuffer, ptr blitterRef, int * quality) = kern_return_t toolbox fn IOFBBeamPosition( ptr blitterRef, UInt32 options, SInt32 * position ) = kern_return_t toolbox fn IOPSBlitFill( ptr blitterRef, int dst_x, int dst_y, int width, int height, int data ) = kern_return_t toolbox fn IOPSBlitIdle( ptr blitterRef) = kern_return_t #endif local fn GetIterator(serviceName as str255, ikey$, ivalue$, matchingServices as ^io_iterator_t ) dim as kern_return_t kernResult dim as mach_port_t masterPort dim as CFMutableDictionaryRef classesToMatch dim as CFStringRef key, value // Returns the mach port used to initiate communication with IOKit. kernResult = fn IOMasterPort( _MACHPORTNULL, @masterPort ) long if ( _KERNSUCCESS != kernResult ) print "IOMasterPort failed" exit fn end if 'setting of the Service Name fn FBPStr2CStr( serviceName ) // -> CString classesToMatch = fn IOServiceMatching( @serviceName ) // filter of the list with the service's class name to match long if ( classesToMatch == _nil ) kernResult = _KERNFAILURE print "IOServiceMatching returned NULL dictionary" exit fn xelse key = fn CFStringCreateWithPascalString( 0, ikey$, _kCFStringEncodingASCII ) value = fn CFStringCreateWithPascalString( 0, ivalue$, _kCFStringEncodingASCII ) long if ( key == 0 ) or ( value == 0 ) kernResult = _KERNFAILURE print "CFStringCreateWithPascalString failed" exit fn end if fn CFDictionarySetValue( classesToMatch, key, value ) fn CFRelease( key ) fn CFRelease( value ) end if // This creates an io_iterator_t of all instances of our drivers class that exist in the IORegistry. kernResult = fn IOServiceGetMatchingServices( masterPort, classesToMatch, #matchingServices ) if ( _KERNSUCCESS != kernResult ) then print "IOServiceGetMatchingServices failed" end fn = kernResult '~'1 dim as long loop dim as SInt32 position dim as io_iterator_t Iterator dim as io_object_t Service dim as int quality dim as ptr blitterRef dim as kern_return_t kernResult dim as long w, h, bps, i long if ( fn GetIterator( "IOFramebuffer", "IONameMatched", "display", @Iterator ) == _noErr ) // Get the first item in the iterator. Service = fn IOIteratorNext( Iterator ) while ( Service != 0 ) print "Service: "; Service kernResult = fn IOPSAllocateBlitEngine( Service, @blitterRef, @quality) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "IOPSAllocateBlitEngine failed" xelse print "Accelerator Service Blitter Ref: "; blitterRef print "Accelerator Service Quality: "; quality 'blocks the access to the display from other applications kernResult = fn CGDisplayCapture(0) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "CGDisplayCapture failed" end if w = fn CGDisplayPixelsWide(0) h = fn CGDisplayPixelsHigh(0) bps = fn CGDisplayBitsPerSample(0) for i = 0 to 2^bps loop = 0 do kernResult = fn IOFBBeamPosition( blitterRef, 0, @position ) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "IOFBBeamPosition failed" end if loop++ until (position > h) or ( loop > 10000 ) // IOFBBeamPosition doesn't seem working on Intel we need a way to escape the loop kernResult = fn IOPSBlitFill( blitterRef, 0 , 0, w, h, i * (1 + 2^bps + 4^bps) * (i mod 2) ) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "IOPSBlitFill failed" end if kernResult = fn IOPSBlitIdle( blitterRef ) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "IOPSBlitIdle failed" end if next i kernResult = fn CGDisplayRelease(0) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "CGDisplayRelease failed" end if end if // Release the io_iterator_t now that we're done with it. kernResult = fn IOObjectRelease( Service ) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "IOObjectRelease failed" end if // Get the NEXT item in the iterator. Service = fn IOIteratorNext( Iterator ) print "----------------------" wend // Release the io_service_t now that we're done with it. kernResult = fn IOObjectRelease( Iterator ) long if ( _KERNSUCCESS != kernResult ) print hex$( kernResult ) print "IOObjectRelease failed" end if xelse print "GetIterator failed" end if stop 2011/2/28 Edwards, Waverly <Waverly.Edwards@...>: > > I really meant to warn everyone not to perform experiments with flashing if they are seizure prone. That was an important thing that I should have stated. Interesting, in the papers I have read over the years, I had not seen healthy adults being susceptible to seizures due to photic stimulation. > > Yes, 60Hz is the upper limit. It is pretty demanding on a machine to update a large portion of the screen. In practice, I have been able to update the 70% of the screen by width at 18.5Hz consistently. I still need to get to 22Hz as another threshold. As I reach 80% of the screen, I can no longer maintain that refresh rate on my 2GHz Macbook. I will be forced to use less screen real estate if I am to get to 22Hz. > > Thanks Herbie for looking out. > > > W. > > -----Original Message----- > From: futurebasic@... [mailto:futurebasic@...] On Behalf Of H. Gluender > Sent: Monday, February 28, 2011 4:40 AM > To: FB Mailing List > Subject: Re: [FB] suggestion sought > > Waverly wrote: > > "The basic idea behind this experiment was drawn > from research such as this. My experiments do > not follow > these experiments precisely but are drawn from them. > > http://www.biomedcentral.com/1471-2202/7/21 > " > > Two remarks: > > 1. > Please be extremely cautious with alpha-rhythm > whole field flicker because it can provoke > epileptic seizures even in healthy persons. > > 2. > In general your temporal resolution is limited by > the refresh rate of your LCD-display which > generally is 16.67 milliseconds (60Hz). > > HTH > -- > > > H. Glünder > > ------------------------ > > <http://www.gluender.de> > > -- > To unsubscribe, send ANY message to: futurebasic-unsubscribe@... > To access the list archives, go to: http://freegroups.net/groups/futurebasic/ > > > -- > To unsubscribe, send ANY message to: futurebasic-unsubscribe@... > To access the list archives, go to: http://freegroups.net/groups/futurebasic/ > >